It was hailed a breakthrough in urban wind power: a 42-storey tower with built-in turbines to deliver 8% of its electricity needs. But today the Strata tower in south London found itself becalmed when it was named Britain's ugliest new building, pipping a rival that the judges said resembled a giant pair of buttocks and a bus station that looked like a jelly mould.

Justin Black, the director of the developer Brookfield had already admitted: "It's what I term Marmite architecture – you either love it or you hate it." And sure enough the judges of the Carbuncle Cup, architecture's least sought after prize, opted for the latter.

"Decked out with Philishave stylings, this is a building that appears to be auditioning for a supporting role in a James Bond title sequence," said Ellis Woodman of Building Design, the trade newspaper which organised the prize.

The building was nominated by The Georgian Group for its "plain visual grotesqueness". Adam Jones, another nominator, said: "I used to live in south London and moved partly because — and I'm not joking — the Strata tower made me feel ill and I had to see it every day."

The dubious honour, now in its fifth year, is intended as an antidote to the Royal Institute of British Architect's Stirling Prize for the best building and has attracted growing levels of interest. Design critic Stephen Bayley said it "attracts a far higher level of intelligent participation than the Stirling prize".

Thirty-one buildings were nominated by readers "united in their often poetic expressions of outrage", said Woodman. The shortlisted Cube office development in Birmingham was described by its nominator as like "a lumpy beige ornament your father buys your mother for her birthday because he thinks it's classy, whereas she can see it for the tat it is".

For the winner, there was the difficult question of how to react. Robert Torday, the marketing director of the apparently unamused architects of the scheme, BFLS, declined to comment.

And not everyone is sure the award is a good thing.

"Labelling one architect with having produced the worst building of the year without mention of the client, developer or contractor means giving the architect a massive kicking when they are very rarely the sole author of the project," said Charles Holland, director of FAT Architecture. "Nothing wrong with robust criticism, but laughing at other people's mistakes is never an edifying spectacle."